Screw taper drill attachment



J. A. LABBEE, JR

SCREW TAPER DRILL ATTACHMENT Filed Feb. 16, 1951 FIG. 3

%@/M ATTORNEY Patented Oct. 20, 1953 UNITED STATES NT OFFICE ment for drilling a screw-receiving countersunk hole.

The principal object of the invention is to provide a simple and efiective screw taper drill attachment which includes a countersink and an automatic stop device.

Another object of the invention is to provide a drill element of special shape, which eliminates the need for a leader hole and a piercing hole, and which provides a strong screw thread lock.

A further object is to provide a simple drill assembly which may be readily mounted in a standard chuck.

With the above and other objects and advantageous features in view, the invention consists of a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawings, and more specifically defined in the claims appended thereto.

In the drawings,

Fig. is a perspective view of one embodiment of the novel attachment;

Fig. 2 is a side view of the head thereof;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a bottom plan view of Fig. 2;

Fig. 5 is a perspective view of the drill blank; and

Fig. 6 is, a perspective view of the drill.

It has been found desirable to provide a screw taper drill attachment which is preferably made of high speed steel and which has a countersink and a stop. To this end, I blank out a drill element of special form, and I utilize a head in which the drill element is mounted and lock swaged, to provide an attachment which can be readily mounted in a standard drill chuck. The drill is basically of the same taper as the body of the screw which is intended to be used, whereby the screw can. enter for its entire length and cut a threaded seat without breaking the screw or splitting the wood or other material, whereby need for a piercing hole and a leader hole 1s eliminated.

Referring to the drawings, the novel attachment it includes a head i i and a drill elementlZ. The head H has an upper shank it for insertion into a standard drill chuck, and a base i l of cylindrical form which has a vertical diametral slot 15, the base and the shank being drilled to provide an axial cylindrical bore 16, and the lower surface I! of the base being plane to function as a drill stop.

lhe drill element 62 is preferably stamped of high speed steel, and includes an upper laterally extending rectangular key l8 adapted to seat in the slot i5, an upwardly positioned projection i9 adapted to seat in the bore 16, a shank 2b which has an upper portion 2.90; with lower edges 2i, 22 inclined downwardly to provide countersink edges and a lower portion 2% which is a shank clearance portion, and a depending drill tip 23 which is tapered and is then twisted as indicated at 24 in Fig. 6 to correspond to the body shape contour of the screw opening to be cut and with a beveled end and to provide spiral cutting edges, the resulting screw opening being preferably equal to or very slightly less than the size of the screw body to permit a firm locking of the screw in the screw opening. The projection i9 is locked in the bore id by swaging or indenting the shank it as indicated at 25 in Fig. 1.

It is clear that the drill element i2 will make a tapered hole in wood, plastic, brick, aluminum, zinc, White metal, and similar materials, the size of the hole corresponding to the body size of the screw to be threaded therein, and that the hole is countersunk to the desired depth, as the lower surface of the head acts as'a stop gage. Since the hole is gaged to properly receive the lock screw, the lock between the screw threads and the material is continuous and uniform throughout the entire length of the screw and the holding power is strengthened.

Although I have described a specific constructional embodiment of the invention, it is obvious that changes in the size, shape and material of the parts may be made to suit the requirements for different screw receiving openings, without departing from the spirit and the scope of the invention as defined in the appended claims.

I claim:

1. A drill element of fiat sheet metal stock for a screw taper drill attachment, said drill element having an upstanding projection, a shank having an upper and a lower portion, said upper and lower portions being in the same plane, and a depending drill tip tapering downwardly and twisted to conform to the body contour of a screw and.

having spiral cutting edges, said upper shank portion having lower countersink edges and said lower shank portion conforming to the shank contour of a screw.

2. A drill element of fiat sheet metal stock for a screw taper drill attachment comprising a shank 3 having an upper and a lower portion, said upper and lower portions being in the same plane, and; a depending drill tip tapering downwardly and twisted to conform to the body contour of a screw and having spiral cutting edges, said upper shank portion having lower countersink edges and said lower shank portion conforming to the shank contour of a screw, and means on said shank for mounting said element in a rotatable sup-- port.

JOSEPH A. LABBEE, JR.

Name Date Lewis J3.eo. 4,186.6

Number Number Name Date Monson June 14, 1870 Southwick Jan. 24, 1882 Champion May 17, 1889 Latham Dec. 23, 1902 Wagner Dec. 17, 1912 Schubnel Jan. 1, 1924 Myers Apr. 28, 1925 iElQRrEIGN P'AIIENTS *Gountry Date Germany Mar. 10, 1879 Australia Jan. 15, 1926 .Great Britain Sept. 9, 1926 Germany Nov. 19, 1936 

